La2(MoO4)3@C as novel anode for lithium ion battery: Structural and chemical evolutions upon electrochemical cycling

La-2(MoO4)(3) is a kind of transition metal molybdate. It has been proved to be a possible anode material for lithium ion batteries due to the high theoretical capacity. In this work, molybdenum-based La-2(MoO4)(3) material is successfully synthesized through a traditional solid-state reaction method. Carbon-coated La-2(MoO4)(3) is designed by using glucose as carbon source. By comparing the carbon-coated La-2(MoO4)(3) with the carbon-free La-2(MoO4)(3), carbon-coated La-2(MoO4)(3) delivers better cyclic stability and rate performance. Carbon-coated La-2(MoO4)(3) obtains a reversible charge capacity of 525.9 mA h g(-1) at 100 mA g(-1) after 100 cycles, corresponding to capacity retention of 75.2%. However, the capacity retention of carbon-free La-2(MoO4)(3) is only 33.4%. The results indicate that carbon layer can evidently alleviate the irreversibility of structure and improve capacity retention of La-2(MoO4)(3). It demonstrates that the carbon-coated La-2(MoO4)(3) composite can be a possible anode candidate for high capacity lithium ion batteries. In addition, in-situ X-ray diffraction investigation (XRD), ex-situ X-ray photoelectron spectroscopy (XPS), and ex-situ transmission electron microscopy (TEM) are employed to analyze the electrochemical behavior during process of cycling. These experimental results indicate that the conversion behavior of La-2(MoO4)(3) upon lithiation/delithiation is a process of structural pulverization. Based on that, our work provides guidance for the research of molybdenum-based electrode materials.

La₂(MoO₄)₃是一种过渡金属钼酸盐。由于其较高的理论容量，它已被证明是一种可能的锂离子电池负极材料。在这项工作中，通过传统的固相反应法成功合成了钼基La₂(MoO₄)₃材料。以葡萄糖为碳源设计了碳包覆的La₂(MoO₄)₃。通过比较碳包覆的La₂(MoO₄)₃和无碳的La₂(MoO₄)₃，碳包覆的La₂(MoO₄)₃表现出更好的循环稳定性和倍率性能。碳包覆的La₂(MoO₄)₃在100 mA g⁻¹的电流密度下循环100次后可获得525.9 mA h g⁻¹的可逆充电容量，对应的容量保持率为75.2%。然而，无碳的La₂(MoO₄)₃的容量保持率仅为33.4%。结果表明，碳层可以显著缓解结构的不可逆性并提高La₂(MoO₄)₃的容量保持率。这表明碳包覆的La₂(MoO₄)₃复合材料可能是高容量锂离子电池的一种潜在负极材料。此外，采用原位X射线衍射研究（XRD）、非原位X射线光电子能谱（XPS）和非原位透射电子显微镜（TEM）来分析循环过程中的电化学行为。这些实验结果表明，La₂(MoO₄)₃在锂化/脱锂过程中的转化行为是一个结构粉碎的过程。基于此，我们的工作为钼基电极材料的研究提供了指导。